1. Field of the Invention
The present invention relates to a stretchable synthetic polymer composite filament. More particularly, the present invention relates to a stretchable synthetic polymer composite filament which has an excellent elasticity and touch but no crimping property, and can be readily handled.
2. Description of the Related Art
Recently, sport wear and stockings are required to have various improved functions, especially a high stretchability.
Two methods are known of imparting a stretchability to artificial filaments. In one such method, the artificial filaments are cubically crimped, and the crimps are imparted to the artificial filaments by a mechanical crimping method, for example, false-twisting, fluid-crimping, or gear crimping, or a thermal crimping method, for example, anisotropic cooling or heating, two different polymer bi-metal structure-crimping or two different polymer eccentric core-in-sheath structure-crimping.
In another such method, stretchable filaments are produced from elastic polymers, for example, natural or synthetic rubber or a synthetic elastomer, for example, polyurethane elastomer. This type of stretchable, filament is disadvantageous in that the rubber or polyurethane elastomer filaments per se exhibit a very poor wearing and knitting processability and a poor dyeing property. Therefore, the disadvantage of the rubber or polyurethane elastomer filaments is avoided by covering the rubber or elastomer filament with another type of filament having a satisfactory processability and dyeing property.
The mechanical and thermal crimping methods are not always satisfactory in view of the functional and physical properties requirements of synthetic filament stockings. Namely, the mechanical crimping methods are disadvantageous in that the thickness and light transmittance of the resultant stretchable fabric are greatly changed when stretched and released, the light transmittance of the fabric is unsatisfactory when released and the stretching stress generated due to the crimps of the filaments is unsatisfactorily low; this low stretching stress results in an unsatisfactory fit and touch of the resultant fabric clothes when worn.
The stretchable filament fabrics produced from the elastomer filaments yarns or composite yarns consisting of elastic filament yarns covered or doubled with another type of yarn having different mechanical and dyeing properties and touch than those of the elastomer filament yarns, exhibit a satisfactory fit and touch when worn. However, in the doubled yarns, the elastomer filament yarns exhibit a poor compatibility with doubling yarns and, therefore, the doubled yarns often generate problems in the knitting process. Also, the doubled yarn knitted fabric exhibits an unsatisfactory light transmittance.
The stretchable fabric made of the covered elastomer filament knitted fabric exhibits a satisfactory fit and touch when worn, and light transmittance, but these covered elastomer filaments are disadvantageous in that the covering process has a low efficiency and thus is very costly.